1. Field of the Invention
The present invention relates to a mechanism, incorporated in a retractable photographing (imaging) lens (retractable lens barrel), for retracting a part of a plurality of optical elements, constituting a photographing optical system, to a position deviating from the photographing optical axis of the photographing optical system when the photographing lens is fully retracted. The present invention also relates to a mechanism, which can be incorporated in a photographing lens, for positioning a supported element such as an internal element of the photographing lens.
2. Description of the Related Art
Miniaturization of lens barrels incorporated in optical devices such as cameras has been in increasing demand. Above all, further miniaturization of retractable photographing lenses, specifically the length thereof in a non-operating state, has been in strong demand. To meet such demands, the inventor of the present invention has proposed a retractable photographing lens disclosed in U.S. patent application Ser. No. 10/368342 in which an optical element of a photographing optical system is retracted to a position deviating from the photographing optical axis of the photographing optical system, and at the same time, the optical element (together with other optical elements of the photographing optical system) is retracted toward a picture plane when the photographing lens is fully retracted. The mechanism achieving such complicated operations of the optical elements is required to operate with a high degree of accuracy. Moreover, it is required that the position of the retractable optical element can be easily adjusted with a high degree of positioning accuracy with a simple structure. Furthermore, it is required to provide the photographing lens with a simple two-dimensional positioning device with which the position of a supported element (e.g., a movable lens frame or holder) can be adjusted two-dimensionally in directions along a flat plane.